Aaron Brookner’s lovely documentary starts out as one thing and then becomes several others. It is an exploration of a life cut short that also offers an elegy for a vanished New York. The archive footage is to be cherished. The emotional kick is substantial. It’s nice that there still are such things.

Aaron is the nephew of the late film-maker Howard Brookner. Throughout the 1980s, Uncle Howard was a significant force in the downtown scene. A gay man from a posh bit of New York City, he wrote his university thesis on William S Burroughs and then went on to track the great writer down in his urban lair.

Brookner persuaded him to participate in a documentary that, released in 1983 as Burroughs: The Movie, became an arthouse hit. Later, Howard managed to gain access to the avant-garde theatre maker Robert Wilson and shot another accomplished documentary on that very different enigma.

In 1989, shortly after completing Bloodhounds of Broadway, a Damon Runyon adaptation featuring Madonna and Matt Dillon, Brookner died of Aids at the wretched age of 35.

The film begins with Aaron trying to persuade John Giorno, the poet who guards Burroughs’s archive, to open up the records housed in a bunker just off the Bowery. Some movement eventually takes place and memorialising begins.

Aaron’s personal story is spun out with great subtlety. Howard’s mother is disarmingly frank about the shock she and her family felt when they learnt their son was gay. Brad Gooch, Howard’s stunningly well-preserved boyfriend, offers first-person testimony on the suffering of the Aids years.

This is much celebration here, too. Jim Jarmusch, who worked on Burroughs: The Movie, is on hand to remind us of the years when you couldn’t step backwards in the East Village without standing on Patti Smith, Laurie Anderson or John Cage. All those appear in a film that, though investigating an era in the relatively recent past, feels like a missive from another millennium.